Do genetic data prove that there are multiple biological races in humans today?
This post is in response to Welcome to Genetic Crossroads by Jesse ReynoldsOn May 5th, 2014, I shared the platform in a webinar debate with Nicholas Wade (former NYTimes Science Writer) about his new book “A Troublesome Inheritance – A discussion on genes, race and human history.” The debatewas sponsored by the American Anthropological Association.
Wade’s assertions in the book (and our discussion) are that Humans are divided into genetically identified “continental races” and that there are significant differences in genetically based social behaviors between these “races” as a result of the last 50,000 years of human evolution.
Wade argues that social scientists are covering up these ideas and claims that a true discussion on race is repressed by most academics out of political correctness. These points were also made by Charles Murray in a laudatory review of Wade’s book in the Wall Street Journal. They are both wrong.
I am an academic and I love to talk about the data on race, so do many of my colleagues. The scientific data on human genetic variation and human evolution refute the claims there are multiple biological races in humans today and in the debate I offered articles, datasets, and work by biologists, geneticists, evolutionary theorists and even anthropologists to demonstrate this. Unfortunately, in such discussions the bulk of data, and its complexity, are too often ignored.
Avoiding direct challenge is a common tactic by people trying to use select slices of genetic data to “prove” that there are multiple biological races in humans today. This is a problem because dialogue on such an important topic should be encouraged and as open minded as possible, but it must also be accurately informed by the science of human biology. So here is a mini-primer on what we what we know about human genetics to help such a discussion (see the bibliography at the bottom of this post for very good articles on the topic).
1) Genes matter, but they are only a small part of the whole evolutionary picture and focusing on DNA segments won’t get you very far in understanding human evolution. The roundworm C. elegans has about 20,000 genes and humans have about 23,000 genes—it is pretty obvious that humans are more than 15% more complex than roundworms.
2) When making scientific argument about genetic variation you need to focus on populations–and be clear about your definitions (a common one for “population” is a geographical cluster of people who mate more within the cluster than outside of it). Many people talking about this subject use the words cluster, population, group, race, subrace and ethnicity in a range of ways, with few concrete definitions and occasionally interchangeably. If you do not define something then you cannot measure it, test for it, or try to construct and refute or support hypotheses for it—in short you can’t do science.
3) Humans all share 100% same genes and 99.9% of the variation in the DNA. So the variation we are interested in is .1% of the entire genome. And yes, understanding that variation is important
4) Most genetic variation is due to gene flow and genetic drift so the further apart two populations are the more likely they are to have more differences
5) Nearly all the genetic variation in our entire species is found in populations just in Africa, with most of the variation found in all populations outside of Africa making up a small subset of that variation.
Given these facts, here is the key argument you need to remember: While different populations vary in some of the .1% of the genome, the way this variation is distributed does not map to biological races, either by continent or otherwise.
For example, when you compare people from Nigeria, Western Europe and Beijing you do get some patterned differences…but these specific groups do not reflect the entire continental areas of Africa, Europe, and Asia (the proposed “continental races” of African, Caucasian and Asian). There are no genetic patterns that link all populations in just Africa, just Asia or just Europe to one another to the exclusion of other populations in other places. If you compare geographically separated populations within the “continental” areas you get the same kind of variation as you would between them. Comparing Nigerians to Western Europeans to people from Beijing gives us the same kind of differences in variation patterns as does comparing people from Siberia, Tibet and Java, or from Finland, Wales and Yemen, or even Somalia, Liberia and South Africa— and none of these comparisons demonstrates “races.”
In fact if you use the common level of genetic differentiation between populations used by zoologists to classify biological races (which they called subspecies) in other mammals, all humans consistently show up as just one biological race.
We do need to talk about Race without fear and with clarity. We certainly need more public discussions on Race, not less. But in doing so we need to accurately represent what the social and biological sciences actually tell us about genetic variation, about race, and about evolution.
Here are some great, but understandably complex, sources to get data and insight on genetics and race:
Bolnick DA. (2008) Individual ancestry inference and the reification of race as a biological phenomenon. In: Koenig B, Lee S, Richardson S, editors. Revisiting Race in a Genomic Age. New Brunswick: Rutgers University Press. pp 70-88.
Buchanan, AV., Sholtis, S. Richtsmeier, J,and. Weiss, K. (2009) What are genes “for” or where are traits “from”? What is the question? Bioessays. 2009 February ; 31(2): 198–208. doi:10.1002/bies.200800133
Nievergelt CM, Libiger O, Schork NJ (2007) Generalized analysis of molecular variance. PLoS Genet 3(4): e51. doi:10.1371/journal.pgen.0030051
Sarah A. Tishkoff et al. (2009) The Genetic Structure and History of Africans and African Americans. Science 324, 1035
Weiss, KM and Long, JC (2009) Non-Darwinian estimation: My ancestors, my genes’ ancestors. Genome Res. 2009 19: 703-710 doi:10.1101/gr.076539.108
Xing, JW, Watkins, S, Witherspoon, DJ et al.(2009) Fine-scaled human genetic structure revealed by SNP microarrays Genome Res. 19: 815-825
